Effect of orientation of initial principal stress on undrained shear behavior of saturated silt

By using the soil static and dynamic universal tri-axial and torsional shear apparatus, the stress-controlled undrained static torsional tests are performed on Dongying intact saturated silt of Shandong province and remolding saturated silt prepared by tamping method controlling three kinds of the initial sampling water contents. The conditions of the initial anisotropic consolidation are the initial mean principal stress of 100 kPa, the initial intermediate principal stress coefficient of 0.5, the initial deviator stress ratio 0.433 and the initial orientation angle of the principal stress respectively at 0^o, 30^o, 45^o, 60^o, 90^o. During the undrained monotonic shearing process, the mean principal stress and the intermediate principal stress coefficient are fixed. The effects of orientation of the initial principal stress and initial sampling water content on the stress-strain relations, the pore pressure development as well as the effective stress paths are studied. The test results show that the effect degree of the initial principal stress orientation on deformation and strength behavior of intact silt is different from that of the remolding silt. The initial sampling water content has considerable influence on the test results of the saturated remolding silt.